


A Dark Edge

by Sinful_ErrorBethy



Category: Undertale (Video Game)
Genre: Abuse, Alternate Universe - Underfell, Anarchy, Blood and Gore, Child Abuse, Dysfunctional Family, Healing, Implied/Referenced Rape/Non-con, Other Additional Tags to Be Added, Pain, Sans will appear after a few chapters, Self-Hatred, Self-Indulgent, Souls, Underfell Sans, Unethical Experimentation, Violence, WWIII has already happened, attempted suicide, skeleton tail, the surface is worse than the underground
Language: English
Status: In-Progress
Published: 2017-06-01
Updated: 2017-06-17
Packaged: 2018-11-07 20:08:20
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 6
Words: 4,226
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11066211
Author URL: https://archiveofourown.org/users/Sinful_ErrorBethy/pseuds/Sinful_ErrorBethy
Summary: Beth has had it rough her entire life.  Her family was abusive, and she's given up hope on things getting better.  That is, until a certain glitch comes over and takes her to the underground.Will she be able to feel true happiness?(Beth's backstory.)





	1. The Pain

**Author's Note:**

> Alright, let's get this started! I'm starting off the story while she's a child. Things will end up getting progressively worse, and then things'll get better for her. Until then, she shall suffer.

6 Years Old

Beth looked at her parents in confusion. They didn’t start beating her up as soon they woke her up this morning. Instead, they just strictly told her to wear this strange white gown. She did as she was told, and they had grabbed her by the arms to drag her to a strange room in the basement. This was where she was now. The room was fairly empty, save for a few shelves that held things that Beth has never seen before. She was strapped onto a cold, metal table and she was unable to move. Her parents were watching through a strange window that was on one of the walls. They gave her cold, blank stares, making her even more confused.

Was this some sort of new punishment they had in mind? If so, how bad would it be, exactly? She jumped slightly when her mother moved away from the window and opened the door to the room. She entered and closed the door behind her. Beth looked at her mother with fear in her eyes. She knew better than to speak. If she said anything, she’d end up with an even worse punishment. Her mother didn’t speak a word to her and pulled out a needle. She got a few of the things off of one of the shelves, mixing them together. She jabbed the needle into the mixture, and Beth could only stare at the dark pink substance that filled the tube.

Her mother came to Beth’s side and searched for a vein. Beth started to panic a little. She was going to put that dark pink stuff into her, wasn’t she? What was it going to do to her? Her mind filled with the endless possibilities of what could happen. She was snapped out of her thoughts when she felt the needle push into her arm. A few seconds later, she felt a burning sensation coming from her arm. It spread quickly to the rest of her body, and she started to thrash and scream. The pain was too much. It was agonizing! The pain seemed to be the worst at her chest. All her mother did as her daughter went through so much agony was write down what was happening.

Beth lost consciousness after a few minutes. She felt relieved about that. When she was asleep or unconscious, she didn’t feel any pain. She felt like she had escaped the hell hole that is her life. She almost wanted to stay in it forever, but there was one thing preventing her from doing so. Her older brother, Mitch.

Admittedly, Mitch wasn’t the kindest person. He was rough, and whenever their parents were watching, he would abuse her. However, it was the moments when her parents were away and they were alone together that she yearned for the most. Those would be the times where he would comfort her and tell her that everything was going to be okay. It made her believe that not everything in this cruel world was horrible. So she would keep on living. If not for herself, then for her brother.


	2. A Painful Realization

**Summary for the Chapter:**

> When Beth grows older, she realizes things that she wishes she hadn't.

15 Years Old

Beth had learned a lot while she was growing up. She found out that she was being experimented on, and that it wasn't right at all. The effects of the many experiments have already taken a toll on her body. Her teeth and nails had become painfully sharp. Her eyes had turned a bright red color, the same color as her soul, or so her brother told her. She had no idea what that meant, but it didn't matter to her now. She had also grown a long, sharp, spiked skeletal tail. Even her hair had been affected. Before the experiments started, it was a light brown color. Now it was jet black.

Her personality had changed as well. She used to be fairly softspoken as a child. She wouldn't speak unless she was told to, and she'd try to stay out of the way. Now, she was a loudmouth. She had become particularly fond of puns and sarcasm, and it gave her a sick satisfaction to see the outraged expressions on her parents' faces whenever she talked back to them. She had become guarded, not showing any emotion towards her parents. She would lash out at people she didn't know who tried to talk to her. She had pulled pranks on her brother as well, who had also changed over the years. When she was a child, her brother was the only kind thing in this world. He would even heal some of the wounds he and her parents had given to her. His hands would glow green and the open wounds that he touched would close up. Now, he was an asshole. He had stopped comforting her. He called her horrible derogatory things and hit her even worse, especially when their parents weren't home. It had pained her when it first happened, but she soon learned to just take it. If she got upset, it would make things worse.

She opened the door, her clothes tattered and a tired expression on her face. She had gone to take a walk in order to get some fresh air. Some assholes had tried to rob and kill her, but she had fought back. She didn't kill them, though. She refused to stoop that low. Instead, she had tied them up and left them there to rot. Though, more likely than not, they would be found by some other people who were looking for some free EXP. The thought disgusted her a bit.

In this world, it's kill or be killed. It had been that way ever since World War III ended. Neither side had won, and everyone was left bitter. Any government that was left ended up overthrown by the enraged spiteful citizens. There were no laws or rules here anymore. Just chaos. Even the "police" didn't do anything. They just used their status as an excuse to be violent and cruel. All the prisons had been abandoned long ago.

She had only taken a few steps into the house when she noticed a strong smell. She recognized it all too well. It was the smell of blood and guts. She tried to find where the source was. It was coming from the lab in the basement. She walked down there and peeked inside of the room. Her hands immediately flew up to her mouth to prevent any noise from escaping her as her eyes widened from the shock.

Her brother was standing there in the middle of the room, covered in blood. He was wearing black leather clothing that she had never seen him wear before. In front of him were two mutilated corpses. They were her parents. It also seems like they suffered before they died, even though she admitted to herself that she didn't really care about that much. What she did care about, though, was the fact that her brother had killed their parents in cold blood. Mitch looked up, and Beth froze when he looked at her. His eyes were glowing black and they showed nothing but hatred. She turned around and made a run for it. She heard the lab door open from behind her, and she knew that he was chasing her. She took the steps two at a time as she sprinted towards the front door. She was only a few steps away from freedom when she felt strong arms grab her from behind and squeezed her tightly.

"Now you listen here, you little whore. Now that mom and dad aren't around anymore, you listen to whatever I say. You will address me as 'sir', and I will punish you if I don't feel like you're doing a good enough job. Do you understand?" he growled in her ear harshly. She gave him a shaky "yes" in response. "YES, WHAT?" he screamed. "Y-Yes sir!" He let her go and walked out the door. All Beth could do in her fear and shock was collapse onto the floor, immediately curling up into a fetal position. She struggled to keep her eyes open, and everything faded to black.

**Notes for the Chapter:**

> Beth is really having a bad time.


	3. All Caught Up

**Summary for the Chapter:**

> Beth's still having a bad time.

Beth walked down the dirt path to her house. Well, it was Sir's house, not hers. She grumbled at her own thoughts. She had been putting up with his shit for years now, and she was now nineteen years old. She still remembers the name of her brother, but she can and will never use it again. Her clothes were bloody, which had become normal over the years. After all, there was no use getting rid of the stains when there'll just be more of 'em the next day.

Today had been pretty exhausting, but not the worst day she's ever had. She had walked the perimeter of Sir's "territory", and she killed any trespassers who tried to attack her. Despite her not being allowed to rest, Sir had built a little station that was fairly cozy right at the midway point of her patrol. She knows that it's just a test to see if she'd disobey his orders, but she always jumped at the chance to get some rest. After all, she hadn't had a good night's rest in a long time. Of course, in the middle of her nap, Sir had found her. He had woken her up and screamed at her for being a lazy sack of shit and a useless whore. As if she didn't kill anyone today. Sure.

The years had changed her a bit. She stopped being a loudmouth at home, though she'd use it on strangers who weren't trespassing. No, at home, if she even breathed the wrong way, her sir would punish her. He had many "toys" that he liked to use on her. They all hurt like hell. His personal favorite seemed to be the spiked bullwhip that he uses on her back. He never healed her, so there were many scars where she had healed herself. She learned about souls and magic, as well as LOVE. She used the information to her advantage, of course. It made getting rid of intruders much easier, and she sometimes didn't have to kill them. After all, she wasn't the best at killing people from a distance. But she was definitely good at dodging.

She had one ability that Sir wouldn't allow her to use. She was able to teleport. Despite the fact that it was for short distances, he had still deemed it lazy for her to use her teleportation for anything other than battles. So she kept using that ability to a minimum. It did leave her with too much magic to deal with, however. She'd usually just use it to heal herself later on. After all, she was punished every day, and those wounds weren't going to heal themselves. Sir would just let her bleed out and die if she got gravely injured.

She was finally able to see the house. She had made it back safely. Of course, that didn't mean she was safe. Not even close. The house looked worn down, with shingles missing and claw marks on the door. Some of the windows were barred up due to them being shattered. Despite their best efforts, there would still be the occasional person who sneaks in and vandalizes the place. There was evidence of it on the sides of the house, where graffiti had been drawn. Home sweet fucking home. She walked inside to an empty house, and looked at the time. It was four o'clock in the afternoon. She got home on time. Sir wouldn't be home until later, at eight o'clock. She didn't try to escape. She knew it was useless. She couldn't take a nap, either, or else she'd be punished even worse. So all she could really do was wait until her brother gets home.

**Notes for the Chapter:**

> In the original rp, Sir was replaced with Boss. However, I felt like that would make it seem too much like UF Sans, so I changed it. Besides, Beth will be meeting Sans and Papyrus eventually, so it'd be confusing to have two characters that are referred to as "Boss".


	4. What the Fuck is This?

**Summary for the Chapter:**

> Beth meets a certain glitch.

Beth groaned as she looked at the clock once again. It was six o'clock, and she was bored. She couldn't sleep or eat, so she was stuck sitting in a chair in the kitchen. She stared at the blank sheet of paper in front of her. Since she didn't have a real job, she wrote stories and gave them to publishers for some cash. Usually her mind would be flowing with ideas. However, no ideas seemed to form today. It was as if the universe was mocking at her misfortune. If she ever saw someone who was the personification of her universe, she'd flip 'em off and kick 'em where the sun don't shine. She smirked and let out a small chuckle at the thought.

She snapped out of her thoughts when she heard a loud snap from outside. She got up, confused. No one had been anywhere near Sir's property the last time she checked. With a sigh, she decided to look out the window to see if there was anything out there. Her eyes widened at what she saw.

There was a strange girl in front of the house, and she seemed to have a worried expression on her face. Her skin was dark grey, and there were strange things floating around her that reminded Beth of static or glitches. Her hair was short and bright red, and her eyes had red, green, and blue in them. She also seemed to have what looked like red bat wings and a red sharp tipped tail. She was wearing a purple shirt and blue jeans. Beth smirked. Now she had something to do while she waited for Sir to get home. She went over to the door and opened it, stepping outside the house as she let a scowl form on her face.

"Who the fuck are you and why are you here?" Beth growled. Hopefully this freak wouldn't stay around for long. She gave Beth the creeps. Now that she was closer to this mystery person, she noticed a low sound that reminded her of the static from a radio. The girl spoke back to her in a broken, staticky tone. "I'm ErrorBe-ethy, but please call me-e Error," she smirks, showing Beth that she had sharp teeth, "and I was just here t-to see what this version of-of me was like."

Beth stared at Error. Another version of her? How in the fuck did that work? Sure, she had heard of the many worlds interpretation, but she didn't think that it would be real. "W-Well, I don't know why the fuck you'd come to this universe, of all places. In this world, it's kill or be killed," she lightly growled. Why did this alternate version of her creep her out so much?

Error nodded, as if she already knew what this universe was like. "What is your sibling like-ike?" she asked. Beth growled in annoyance. "My brother Mitch? He's an asshole. I've been doing whatever the hell he wants for years now, and I'm not allowed to call him Mitch or brother in front of him. He insisted on the very first day that I called him 'sir'." A glitched gasp comes out of Error's mouth, and Beth groaned. She was a nice person, wasn't she? Fuck.

"You sh-shouldn't have to put up with his crap, even if he is-s your brother!" Error exclaimed. She seemed to think for a minute before her whole face seemed to light up, a genuine smile on her face. "I'll tell you wha-at. I could take you-ou to a place where your brother can ne-ever find you or hurt you again. All you'll have to-o do is give me the okay and follow me-e. Does that sound like a deal?" Beth shakes her head. "Nah. I don't want to leave sir all alone. Thanks for the offer, though." Beth headed back inside, leaving Error outside, speechless.

**Notes for the Chapter:**

> Beth'll hit a breaking point eventually.


	5. Well Shit...

**Summary for the Chapter:**

> Beth breaks down.

**Notes for the Chapter:**

> Warning for this chapter: mentions of rape, suicide attempt

It had been a month since Beth had that strange encounter with that girl. She doesn't remember her name, even though she feels like that it's something she should be able to remember. She shook her head. Things have only gotten worse since then. Sir had been working her even harder and punishing her even more harshly. She knew what he had planned for her today. She shudders at the thought. It was the ultimate form of punishment. She could handle the beatings and harsh words, but she couldn't stand being given unwanted pleasure. It made her sick to her stomach.

So as soon as she got home today, she immediately went into the kitchen, not even bothering to check the time. She searched the drawers, getting increasingly frustrated. She finally let out a relieved sigh when she found where he kept the knives. When Sir had first found her cutting herself, he had scolded her and beaten her. Afterwards, he had hidden all of the sharp objects in the house. Beth looked at the sharp blade, putting her finger to the end of it to test it's sharpness. Her finger bled, and she smiled. This one will do.

She pressed the blade on her wrists, and she sliced them open. She started with the left one, and then went on to the right one. She was bleeding and in pain, but she didn't care. This was nothing to her. She brought the blade up to her neck, cutting that open as well. She felt her energy slowly draining away, and she started feeling very tired. She laid down on the floor and closed her eyes, letting a small smile form on her face. She didn't have the knife in her hand anymore. She assumes that she dropped it at some point. Well, it didn't matter now anyways. She let herself get dragged into the darkness, hoping that she succeeded.

~~~

Beth woke up feeling sore. She groaned slightly and opened her eyes. Well, it seems like her attempt had failed, but... where was she? She looked around. She seemed to be in an unfamiliar bed with a red blanket and black pillows. The room seemed to be only lightly decorated, with a few posters on the walls and a chair facing the bed. She jumped slightly when she noticed that the chair was occupied.

It seemed to be that girl she had met a month earlier. The girl seemed to be fast asleep, snoring lightly. What the hell was she doing here? And where the hell was she, anyways? She looked at her wrists and noticed scars where she had cut herself. She winces slightly. She had gotten really desperate to escape, huh? She sat up, clearing her throat. The girl immediately woke up. "Oh! You're a-awake! I was starting to think you-ou wouldn't after a while." Beth narrowed her eyes at this. She remembered this girl's name now. It was Error. "What do ya mean by 'after a while'?" "Oh! You've been unconscious fo-for about two weeks." TWO WEEKS?! She had never been knocked out for that long before. But that didn't matter right now. What mattered was getting some damned answers.

"Okay then. Where the hell am I and why are you here, Error?" she asked. "Oh! You-ou remembered my name! I gue-uess you don't have the same kind of memory as-s I do. You're at my house in my uni-universe. I wanted to take you somewhere safe so that I-I could heal you," she replied rather enthusiastically. Ah, so that explains it. "Are you oka-ay now?" Did it fucking look like she was okay? She decided to keep the comment to herself, though, seeing the worried look on Error's face. "Not really, but I will be. Hey, that deal you talked about when we met... is it too late to accept?" Error's expression lit up, and she let out an excited squeal. "No, it's not too late! I-I can still take you to the underground."

Well that was good to know. Beth let out a sigh of relief. The thought of never seeing the asshole who started all of this in the first place gave her a sense of relief. Besides, he would be fine on his own. He didn't need her. Error's expression became serious, and Beth shivered slightly. There was going to be some sort of catch, wasn't there? "However, I'm not going to-to be taking you there right now. You need time to rec-cover, so you'll be staying over here for a few days." Oh. Was that it? Beth was expecting some sort of orders or tasks that she'd have to complete.

She gave Error a nod, and she smiles. "That's good. I-I didn't want you to feel like you we-ere being taken as hostage or something. Considering where you grew up-p, I wouldn't have been surprised if you had," she continued. Beth just nodded. This Error girl knew a lot about her world, huh? She kind of wonders how she had gotten the information in the first place, but then shrugged the thought away. It wasn't in her place to ask. Seeing how Error's personality was, she imagined that she was going to have some exciting days ahead of her.


	6. Healing

**Summary for the Chapter:**

> Beth gets better.

**Notes for the Chapter:**

> I'm sorry for not updating much. I can only really write when I have the motivation and the ideas to do it.

It had been two months since Beth first woke up in Error's universe. She learned from Error that the place was called Errortale and that she was the only person in this universe. Beth had explored the world quite a bit. This world seemed to be in ruins once you got past where Error resided. Beyond the trees and many strange creatures and creations, there were destroyed homes, ashes, and dried blood. She had asked Error about it a few times, but every time she asked, Error would glitch more than usual and dismissed her question, simply stating that she was only a survivor of something terrible.

It made sense to Beth that Error had gone through something traumatic. She had woken up quite a few times to Error's glitched screaming. She'd go into her room, and she'd find the glitch tossing and turning in her bed, red magic flowing out of her closed eyes. Beth would wake her up and calm her down. So the glitch had nightmares. Beth wouldn't complain, since she had some of her own. She was more of a silent sufferer, though, and she doubted that Error ever noticed.

The day after Beth had first come here, Error gave her some pills to take. She told her it was to help with her depression. Beth wanted to ask her how she knew about that, but then she remembered that this glitch was literally an alternate version of herself. She was bound to know at least some things about her simply from personal experience. Heck, the pills were probably prescribed to the glitch before whatever the hell had happened to this universe. When she first started taking the pills, not much changed, but Error told her to give it time to work. After about a week, she felt a little better.

Error had shown her some of the different AUs that existed. Seeing herself with blonde hair and a cheerful attitude was really strange to say the least. Error had called that version's AU "Underswap". There was another one that Beth absolutely hated. It showed her acting like her brother. Error had called that place "Swapfell". She kind of wanted to question why the glitch kept naming the places that she showed, but she decided not to. She just assumed that it was one of Error's many odd quirks.

Beth had learned a lot about the glitch while she was here. One of those things was the fact that she couldn't eat or drink anything. Beth had seen her eat a chocolate bar, and she could only watch in horror as Error's form changed. It was as if she were made of some sort of strange goop. Error had glitched a little more before she excused herself to go to the bathroom. Beth just stared at the dark grey puddle that had formed on the floor where Error was just standing. She also found out about Error's red strings. She had gotten behind the glitch and scared her, causing her to end up with her soul entangled in red strings. It felt like her entire being was being squeezed tightly, and it hurt a bit. As soon as Error found out what she was doing, she had immediately let Beth go, apologizing profusely. Beth brushed off her apologies, saying that it was her own fault for startling her.

Immediately after that, she had gone into her room. She sat down on the bed and reached over to her chest. She summoned her soul a bit hesitantly. She had been curious since she briefly saw it tied up in red strings. What she saw wasn't something that she would consider pretty. Her soul looked like a cartoon heart, dull red and dark blue in color. There were various cracks and pieces missing from her soul, and it made her wonder how this thing was even functioning. It seemed like it should've broken a long time ago. Beth winced and put her soul back in her chest. That had not been what she was expecting, and she definitely didn't want to see it ever again.

The days had really flown by, and Beth was sure that it was because she was finally having fun.


End file.
